The tetraspanin CD9 facilitates MERS-coronavirus entry by scaffolding host cell receptors and proteases
(A) LET-1 cells were transduced with an adenovirus carrying a GFP gene or adenoviruses carrying hDPP4 and either an empty vector, the TMPRSS2 gene, or a U6-driven shRNA against TMPRSS2 or CD9. After 3 days, cells were lysed and analyzed by western blot for the indicated proteins. (B) Quantitative rtPCR analysis of Tmprss2 transcripts in cells transduced with rAd5-hDPP4-EV and rAd5-hDPP4-shTmprss2. (C) LET-1 cells were transduced with the indicated Ad5 vector before transducing with VSV-MERSpp. Transduction was measured by luciferase assay. (D) The indicated Ad5-DPP4 vectors were installed intranasally in C57/Bl6 mice. 5 days later, mice were infected with MERS-CoV. Lungs were isolated at 2 dpi and viral titers were measured by plaque assay.